#!/usr/bin/python

nm=raw_input("please enter the width of the cube, in  nanometers: ")
mass=raw_input("Please enter the mass of one mole of the molecule, in g/mol: ")
density=raw_input("Please enter the density of the substance in g/cm^3: ")

nm=float(nm)
mass=float(mass)
density=float(density)

nmol=(density*((nm*1.0e-7)**3)*6.022e23/mass)

print "%.3f molecules" % nmol